Radio transmission with a satellite

(54) Rad ioffeffective link with balance (57) The essence of the solution is a mechanism for the construction of species? networks (101 to 103) and terrestrial forces are characterized by maintaining the power levels received by the terrestrial transmission by about one size order above the transmissions of the shared channel for overcoming, interfering with, and maintaining the subscriber transmissions. to terrestrial networks and at power levels by about one size order below the benefits of a shared channel to satellite networks. to prevent satellite interference (101 to 103). This maintenance of performance levels is created by force in conjunction with the respective participant. In addition, the non-circulating grounded satellite forms a switching node as a satellite sft. (101 to 103) thus a terrestrial network for transmitting information between a terrestrial subscriber and a satellite radiotelephone force (1.0.1 to 103) via a terrestrial network. Terrestrial network and satellite. the network (101 to 103) can be connected either via the internal satellite spectrum or via the terrestrial satellite spectrum rum.

NAME OF THE INVENTION

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Network cellular satellite and terrestrial radiotelephone system

TECHNICAL FIELD The present invention relates to radiotelephone satellite data transmission. In particular, the present invention relates to the construction of satellite networks with a cellular structure and their connection to terrestrial radiotelephone networks.

BACKGROUND OF THE INVENTION

We have previously developed a satellite cellular infrastructure, consisting of an array of satellites orbiting in the low polar orbit of the earth, each satellite having a number of satellite-earth frequencies that irradiate hundreds to thousands of square miles of earth's surface. Each frequency may be reused by both the original satellite and neighboring satellites, provided that a sufficient geographical distance is maintained to prevent interference between terrestrial radiotelephone subscribers.

In this system, the terrestrial subscriber is transmitted from one frequency to another and from one satellite to another, as the constellation of satellites moves across the sky, using switching centers on board the satellites, the satellite orbits are interconnected by high-speed, large inter-satellite bandwidth links. for the overall interconnection of terrestrial talking stations. A more complete description of such cellular satellite systems is contained in our patent application No. 89118458.2, published 02051990.

Because the surface area of ​​the earth irradiated by a single frequency is so large compared to terrestrial cellular radiotelephone systems, satellite cellular systems have a much lower subscriber capacity and therefore have limited utility in low subscriber density and rural markets; urban cellular traffic is much denser and requires higher efficiencies obtainable by spectral reuse.

Due to the high costs of satellite construction, launch, operation and maintenance of satellite infrastructure, the economic ability to offer radiotelephone services via satellites depends on the possibility of integrating terrestrial radiotelephone networks into cellular satellite systems.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome these disadvantages while at the same time creating certain advantages, which will be described below.

If the capacity of satellite connections to terrestrial subscribers could be increased by grounding the satellites and using a larger width x of their inter-satellite band, it would be possible as a result to combine the larger capacity of the terrestrial network with the satellite network to create global cellular communications. Urban traffic should be provided by the terrestrial system, while the global service would be a satellite network everywhere else.

The present invention solves this problem by proposing a method of constructing satellite and terrestrial networks, controlling terrestrial network transmissions against satellite transmissions, overcoming interference, and controlling terrestrial network subscriber transmissions against transmissions to satellite networks, to prevent the causes of satellite interference.

In a preferred embodiment of the method according to the invention, the invention comprises maintaining the level of terrestrial network transmissions received by subscribers by about one magnitude above satellite transmissions, precisely to overcome interference and further maintaining terrestrial transmissions at terrestrial networks at performance levels about one magnitude below satellite transmissions. channels to prevent satellite interference. Such maintenance of the power level is created by the network in connection with the subscriber. In addition, the non-orbiting ground satellite forms the switching node of both the satellite network and the terrestrial network for the transmission of information between the terrestrial subscriber and the radiotelephone satellite network, via the terrestrial network. the terrestrial network and the satellite network may be connected either via the internal satellite spectrum or via the spectrum between the terrestrial and satellite networks.

CLARIFICATION OF THE DRAWING 0

Other advantages and features of the invention will become more apparent and understood from the following detailed description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings, in which:

Giant. 1 is an enlarged view of a satellite network and a terrestrial cellular radiotelephone network according to a preferred embodiment of the invention; FIG.

As mentioned above, the biggest limitation of the satellite radiotelephone network is that the surface of the earth irradiated by one satellite antenna forms such a large block that spectrum utilization is very inefficient compared to terrestrial block dimensions and terrestrial cell frequency reuse efficiency. Each satellite block is several hundred miles away due to the limited ability of the satellite antenna to shape the beam, the present invention increases the efficiency of overall spectrum reuse against the terrestrial cellular network, thereby increasing the economic acceptability of a globally associated cellular radiotelephone service using satellites.

EXAMPLE OF EMBODIMENT OF THE INVENTION

The present invention increases spectral efficiency by reusing the terrestrial frequency of satellite-to-ground frequencies. In the city space 150 shown in FIG. 1 four sets of frequencies are reused / F 1 -? 4, with the number of frequencies in each set / ground in the city space, geographically separated according to the so-called four-cell pattern reuse qraziano, US Fat.no. 4 128 740 about title Antenna; field for the cellular radio transmission system, '' transferred to Motorola, the problem associated with terrestrial use of the satellite spectrum is to prevent interference between satellites and terrestrial stations using the same frequencies. According to the invention, the transmission power is coordinated and controlled so that those transmissions intended for terrestrial networks do not interfere with the transmissions intended for the satellite network.

to prevent interference, terrestrial transmissions are kept about 10 dB higher (at the subscriber) than satellite transmissions, thereby correcting the subscriber's receiver; similarly, the subscriber's transmission powers intended for terrestrial networks are kept sufficiently below the transmissions intended satellite receiver interference is excluded. Furthermore, the subscriber's transmissions below the sensitivity threshold of the satellite receiver will not be audible by the satellite, but will be audible by terrestrial receivers of the same sensitivity due to different loss paths. Thus, by controlling the terrestrial transmission powers relative to the satellite transmission powers and the tariffing for the sensitivity of the satellite receiver, the necessary mechanism is created for the uninterrupted terrestrial reuse of the satellite cell spectrum. The required equipment and control system required for such power control are not dissimilar to those embedded in existing terrestrial cellular radiotelephone networks and subscriber radiotelephone equipment (see U.S. Pat. 4,523,155 to Walczak et al., Transferred to Motorola, and U.S. Pat. 4 6I3 990, Halpern /.

Radiotelephone calls to and from the local ground service area are made by grounding the satellites to the uppermost roofs of the city's structures. Grounded satellites use the same spectrum (earth and ground-satellite) as orbiting satellites (except for those frequencies in the arrays that could be used to create additional capacity).

Fig. 2 shows a subscriber communicating in a satellite network and a terrestrial cellular radiotelephone network according to a preferred embodiment of the present invention. It further illustrates a cellular satellite radiotelephone network - connected to terrestrial radiotelephone networks according to the present invention. The satellite network consists of many satellites / 301, 3Q2, 303, /, orbiting the sky in the low polar orbit of the earth. The mentioned satellites communicate with participants on the ground - several narrowband frequencies / F 1 - F 4, 320, 343 /^and they switch calls between themselves over a broadband spectrum of 300 to 36Ο, eg microwaves IH OF LASER / light /. Shown terrestrial networks, 3lQ,

311, 3I2, 3I3, 3I4, 3I5 may be formed by conventional cellular radiotelephone networks, local radio networks of buildings, public telephone networks, private branch exchanges and the like. Each can be independently connected to the satellite network via a grounded satellite at the top of the building. Furthermore, networks with broadband media, such as microwave links 31, 342 or fibers 350, 351 352, having a single grounded satellite 311 for connection to a satellite network 302 with one or more satellite frequencies iiiV traffic, may be used as terrestrial networks. in addition to covering the terrestrial radiotelephone network 332, it first transmits with sufficient power to reach the satellite receiver 3Q1 in its possible further orbit. The exchange between the satellite and the subscriber will create successive performance levels for the intended use in subsequent transmissions, as the satellite moves across the sky and then out of range. Radiotelephone calls destined for another service area are switched by the original satellite 30 via its inter-satellite connection 305 to the satellite 302 simultaneously serving the intended recipient 330.

Said satellite 302 squats a call over the narrowband satellite-ground frequency 343 to a grounded satellite 3H at the top of the urban structure, which further switches the call via an opto-fiber link 351, 352 and a point-to-point link 317 to the terrestrial cellular network 3I3. The terrestrial cellular network 313 connects the call to the subscriber at a power level about 10 dB above the satellite frequency level 343, while the subscriber responds at a power level low enough not to interfere with the signals returned to the satellite 302. Placing grounded satellites at the tops of tall urban structures reduces the satellite-to-ground transmission power compared to the power required by a street link. However, satellite 302 may transmit signals directly to user 330 at a satellite frequency of 365 li if special ground capacity is required; both the satellite and the subscriber can transmit at a higher power, but this is clearly a less interesting variation when it comes to the battery power of the satellite and the battery power of a portable radiotelephone.

In this way, a mechanism for connecting the satellite and terrestrial cellular radiotelephone networks is provided. Satellite frequencies can be reused terrestrial, with power-controlled differences maintained between satellite and terrestrial transmissions. This will increase the efficiency of spectral utilization. Grounded satellites form a connection to the terrestrial network. Radiotelephone coverage, continuous, global, consists of terrestrial radiotelephone networks in urban service areas and satellites elsewhere, including the aforementioned urban areas without cellular service.

Although power difference control is a preferred embodiment of the invention, other methods of frequency planning for networking are suitable. Advantageously, larger bandwidths of the inter-satellite spectrum can also be reused. The inter-satellite spectrum 305, 306 can connect grounded satellites to orbiting satellites without interference and

- 7 is exploited between grounded satellites 3I7 to 342 due to the lateral routing of the spectrum of inter-satellite links and the perpendicularity of the satellite-ground and ground-satellite links. This further increases the spectral efficiency.

Together with the larger satellite-to-ground bandwidth, grounded satellites can be pre-introduced synchronously into inter-satellite communication, or pre-synchronously inserted into satellite call routing in advance with synchronous live or slow operation and become an integral part of the satellite's switching function.

However, other frequency plans can be created. Conventional terrestrial cellular radiotelephone networks use seven frequency sets in a hexagonal reuse arrangement with one center cell surrounded by six others. If four sets are used in addition to adapting to the situation where the urban area falls at the intersection of four satellite cells, the obtainable cell spectrum can be divided into eleven sets, usable dynamically, synchronously and inextricably by a combined beam-r-height with a frequency-flexible sensor on board the satellite. or the ground or satellite frequency track on the ground cell would need to be changed synchronously each time the satellite passes through the sky to avoid interference. In other words, time-synchronized frequency reuse would have to be used. Although less preferably, this creates a frequency reuse no worse than 7/11 frequency reuse, if the relationship of the near-ground antenna to the 10 dB loss of efficiency is not considered. Other shapes of disjunctive sets of frequency sets or satellite reuse patterns that do not match the terrestrial patterns would create some increase in spectral efficiencies.

For ease of understanding, the description assumes the association of a frequency division multiplexing (FDMA) approach, but a TDMA / FDMA time division multiplexing multiple approach, considered to be compatible with emerging digital cell standards in the United States, Europe, and Japan. Extension to direct sequence, extended spectrum, or code division multiple access (CDMA) would also be acceptable.

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